One of the first things beginners notice when learning Finnish is that word endings seem to change.

Sometimes you’ll see:

• talossa
• koulussa
• Suomesta

But other times you’ll find:

• päivässä
• työssä
• kylästä

At first, this can feel confusing.

Why is it -ssa in one word but -ssä in another?

Why do some words use -sta, while others use -stä?

The answer is something called vowel harmony (vokaaliharmonia). Fortunately, this is one of the easiest grammar rules in Finnish. Once you understand the basic idea, you’ll start noticing it everywhere.

What Is Vowel Harmony?

Finnish vowels are divided into three groups.

Back vowels	Neutral vowels	Front vowels
a, o, u	e, i	ä, ö, y

Back vowels

a	auto
o	koulu
u	lumi

Neutral vowels

e	vene, tee
i	tie, kieli

Front vowels

ä	päivä
ö	pöllö
y	hyvä

The basic rule is simple:

Words with a, o, u usually take endings with a, o, u.

Words with ä, ö, y usually take endings with ä, ö, y.

The neutral vowels i,e can go with both other groups.

Why Does This Matter?

Because many common Finnish endings have two versions.

For example:

Back vowel version	Front vowel version
-ssa	-ssä
-sta	-stä
-lla	-llä
-ko	-kö
-vat	-vät

These endings appear all the time in everyday Finnish.

Words with Back Vowels

Look at these words:

• auto
• koulu
• talo

Since they contain a, o, or u, they use back-vowel endings.

Examples:

• autossa
• koulussa
• talossa
• hallissa

Questions:

• Onko?
• Tuleeko?
• Uitko?

Verbs:

• asuvat
• puhuvat
• voivat

Notice that the endings contain a, not ä.

Words with Front Vowels

Now look at these words:

• päivä
• kylä
• työ

These words contain ä, ö, or y, so they use front-vowel endings.

Examples:

• päivässä
• kylässä
• työssä

Questions:

• Ymmärrätkö?
• Näetkö?

Verbs:

• käyvät
• löytävät

The endings change to match the vowels in the word.

What About Words with Only E and I?

This is usually the next question learners ask.

Words containing only e and i normally will follow the rule of the front vowels group. That means the endings are always ä, ö, y

Examples:

• kielessä
• tiellä
• pienessä

Even though these words don’t contain ä, they still behave like front-vowel words.

This is something you’ll quickly get used to after seeing enough examples.

A Simple Trick

When learning a new word, pay attention to its vowels.

Ask yourself:

Does this word belong to the a-o-u group or the ä-ö-y group?

For example:

• koulu → koulussa
• talo → talossa
• päivä → päivässä
• työ → työssä

This tiny habit will save you a lot of guessing later.

SHORT LESSON FROM SATU LAHTONEN OPETTAJA

Compound Words

Sometimes you may see a word that contains both vowel groups.

For example:

• Vanilja + jäätelö –> vaniljajäätelö
• jäätelö + kioski + –> jäätelökioski

These are compound words.

When adding endings, Finnish usually follows the vowel harmony of the last part of the compound word.

Examples:

• vaniljajäätelössä
• jäätelökioskilla

TIME TO PRACTICE!